Fazt, Based on your description, the vapor pump works in conjunction with the OMS Pump to fill the vapor separator. If the vapor seperator cover has a leak, fuel would not be drawn in, yes? Likewise, without proper function of the vaporpump, the OMS pump would be unable to fill the seperator?
Ok here is run down on how fuel bracket works on 60 degree...(simple version)
When you pump up bulb, fuel is drawn from tank to the inlet filter that is on front side of bracket.(pic 1) As you pump you fill the fuel chamber till it is pressurized by bulb(pic2).Fuel then travels from chamber down rear of bracket and fed into bottom of VRO/OMS pump(pic3)and pump sends it out thru passage in fuel chamber to carb manifolds(pic2) Fuel does not go thru needle and float like a Mercury VST but float opens and closes passage to vapor pump,(pic4) so when you start engine and chamber is full, vapor pump does nothing as float & needle has inlet sealed. As fuel is used and float level falls, vapor pump draws excess vapor from chamber to help prevent a vapor lock condition. If diaphram goes bad or needle/float sticks it can cause bogging problems due to vapors boiling under vacuum (low fuel delivery). The check valves are arranged in vapor pump to prevent vapor separator from venting to atomosphere (vacuum loss)(pic5) Any airleaks in the separator will cause VRO/OMS pumping problems but most will show up buy a fuel leak in the affected area as you can pressurize the separator with primer bulb. I have only seen one cover cracked on these models and it was due to improper reassembly.
